The preparation and properties of crystalline yeast aldolase.

Yeast aldolase was purified partially by Warburg and Christian (I), who found that it was inhibited by metal-binding agents and could be reactivated by addition of Fe++, Co++, or Zn++ ions. Later, this enzyme was further purified, treated with a chelating agent, and crystallized as a mercury salt (2). In this form, the enzyme was still active when tested in the presence of cysteine and Zn++ ions. Rutter and Ling (3) reported the presence of zinc in purified yeast aldolase preparations, and recently a more thorough study of the metal content of this enzyme was made (4). In the preparation of crystalline yeast glyceraldehyde 3-phosphate dehydrogenase by simple ammonium sulfate fractionation (5), the 0.7 saturated supernatant solution, which is ordinarily discarded, was found to contain approximately 40% of the aldolase present in the original yeast extract. This fraction proved to be a convenient source for the preparation of crystalline aldolase by further salt fractionation, and a method for the simultaneous isolation of the dehydrogenase and aldolase was provided (6). As described here, the steps involved in the isolation of glyceraldehyde 3-phosphate dehydrogenase arc bypassed, and a single preliminary salt precipitation of this enzyme, together with other contaminating proteins, is employed.